Self-locking and self-ejecting electric outlet and plug



May 15, 1956 J. M. BUTKOVICH SELF-LOCKING AND SELF-EJECTING ELECTRIC OUTLET AND PLUG 2 Sheets-Sheet 1 Filed May 12, 1955 INVENTOR. John .WLBuihovj/ch I/ M I United States Patent SELF-LOCWG AND SELF-EJECTING ELECTRIC OUTLET AND PLUG John M. Butkovich, Detroit, Mich.

Application May 12, 1955, Serial No. 507,897

2 Claims. (Cl. 339-45) This invention relates to electrical equipment, and more particularly to a self-locking electrical outlet and plug.

The object of the invention is to provide a self-locking electric outlet and plug which is constructed so that the plug will remain securely locked in the outlet until it is desired to remove the plug.

Another object of the invention is to provide a selflocking and self-ejecting electric plug which will automatically lock in the outlet and which can be quickly and easily removed from the outlet when desired, the present invention being especially suitable for use with electrical appliances which use extension cords since the plug will remain firmly locked in the outlet even though the cord is moved.

A further object of the invention is to provide a selflocking plug and an outlet which is extremely simple and inexpensive to manufacture.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this application, and in which like numerals are used to designate like parts throughout the same:

Figure 1 is a front elevational view showing an outlet with a plug arranged in engagement therewith.

Figure 2 is a fragmentary front elevational view of a modified outlet showing circular holes instead of slots as for receiving prongs of cylindrical shape instead of prongs of flat shape.

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a rear elevational View of the outlet.

Figure 5 is a sectional view taken on the line 55 of Figure 2 and with the plug locked in the outlet.

Figure 6 is a view similar to Figure 5 but showing a modification wherein the plug has prongs which are fiat instead of cylindrical.

Figure 7 is a view similar to Figure 5 but showing the prongs released from the outlet.

Figure 8 is a sectional view taken through the outlet with the plug removed.

Figure 9 is a sectional view taken on the line 9-9 of Figure 7.

Referring in detail to the drawings, the numeral 10 designates a portion of a suitable supporting structure such as a floor or wall, Figure 3, and the supporting structure 10 is provided with an opening 11 through which extends a box 14. The box 14 includes the usual wails 13 which have flanges 15 thereon that are seated in a countersunk recess 12 in the support member 10. A cover plate 17 may be secured in place by means of a screw or bolt 18.

The housing 16 which forms part of the outlet is made of insulated material and includes an inner wall 19 and an outer wall 20 which may be interconnected together by wall sections 21.

The numeral 22 designates one of the plugs for use with the outlet, and each of the plugs 22 includes a base 2,745,021 Patented May 15, 1956 23 that has wires or conductors 24 extending therefrom, Figure 5. The base 23 has prongs 25 extending therefrom, and the prongs 25 may have a cylindrical shape so that the prongs 25 can project through circular openings 27 in the outer wall 29 of the housing 16. Or, the prongs may have a rectangular shape as indicated by the numeral 26 so that the prongs 26 may project through slots 28 of rectangular shape as shown in Figure 1.

Secured to the inner wall 19 of the housing 16 are contacts 29 which are adapted to be connected to a suitable source of electrical energy as for example by means of the wires 31. L-shaped ribs 38 extend from the contacts 29 through the wall 19, and the ribs 30 have secured thereto spaced parallel ears 32 which are arranged in pairs. An insulated bar 33 is pivotally connected to each pair of cars 32 through the medium of a pivot pin 34, Figures 5-8. The prongs 25 or the prongs 26 are each provided on their inner surface adjacent their free end, with a notch 35. These notches are adapted to engage shoulders 36 which are formed on each of the insulated bars 33 whereby the plug will be locked in the outlet. Projecting inwardly from each of the bars 35 is a body portion 37, and a coil spring 38 has one end abutting the body portion 37 while the other end of each of the coil springs 38 is seated in a socket or recess 39 formed in the wall 19. Each of the bars 33 is further provided with a finger 46 of reduced size for a purpose to be later described.

Projecting from each pair of cars 32 and secured thereto in any suitable manner, as for example by welding, is a spring member 41. These spring members 41 serve to guide the prongs in their proper position as they are moved through the outlet.

The portion of the wall 20 surrounding the slots 28 may be recessed as at 42 whereby the prongs will be readily guided into the slots 28. Similarly, the portions of the wall surrounding the circular openings 27 may be recessed as at 43 so as to provide a guideway to helpfacilitate the insertion of the prongs in these openings. Extending from the base 23 of the plug 22 and secured thereto or formed integral therewith, is a cylindrical stud 45 which is adapted to project through a circular opening 44 in the wall 20. For coaction with the stud 45, there is provided a plunger 46 which includes a cylindrical portion 47 and a collar 43 of increased diameter. A pin 49 extends from the plunger 46, and one end of the pin 49 is seated in a recess 50 in the wall 19, there being a coil spring 51 circumposed on the pin 49. Securing elements or bolts 54 connect a bracket 52 to the collar 43, and the bracket 52 includes a circular sleeve 53 which is provided with holders 55 for receiving the fingers 40.

From the foregoing it is apparent that there has been provided an electric plug and outlet assembly wherein the plug will not accidentally work loose from the outlet and wherein the plug can readily be released when desired. In use, the plug 22 may be arranged so that its prongs 25 extend through the openings 27 whereby the notches 35 in the prongs 25 will engage the shoulders 36 on the insulated bars 33 as shown in Figure 5 whereby the plug 22 will not accidentally work loose from the outlet even when the electric fixture or cord is moved around. The spring members .1 and springs 38 will tend to urge or bias the shoulders 36 into locking engagement with the notches 35 whereby the plugs will be retained locked in the outlet. it is to be understood of course that the outlet may include a-plurality of similar units so that a plurality of plugs 22 can be used as desired. When it is desired to release the plug from the outlet, it is only necessary to manually push the plug 22 inwardly towards the outlet whereby the stud 45 on the plug 22 will engage the plunger 46 as shown in Figure 7 so that the parts will move from the position shown in Figure 5 to the position shown in Figure 7. As the plunger 46 moves inwardly through the opening 44 in the wall 20, the securing elements 54 will move the holders 55 down until they receive or engage the projecting fingers 4'9 on the bars 33. Then, with the fingers 4% held in the holders 55, the notches 35 will clear the shoulders 36 so that it e prongs 2S and plug 22 can be readily withdrawn from the outlet.

The prongs may have the cylindrical shape as shown by the numeral 25, or the prongs may have a rectangular shape as indicated by the numeral 26. When the prongs have the cylindrical shape, the openings 27 are of circular shape, and when the prongs 26 are of rectangular shape, there is used the rectangular slots 28 instead of the circular openings 27. The spring 51 will return the plunger 46 and its associated parts to the position shown in Figure 8 after the plug has been removed so that the parts are ready to receive the prongs when they are again inserted in the outlet. The springs 3 help maintain the fingers 46 of the bars seated in the holders 55 until the prongs 25 have their notches 35 clear the shoulders 36.

The housing of the outlet may be made of insulated material, and the bars are made of an insulated material.

The holders 55 which form part of the brackets 52 serve to hold the bars 33 in open position until the plug 22 is clear of the bars 33. The leaf springs 41 serve to conduct current or electrical energy from the prongs to the ribs 3%.

In use, the plug is inserted into the outlet until it automatically locks therein. Then, to release the plug, it is only necessary to push the plug firmly into the outlet and the prongs will move the bars 33 inwardly so that the bars will move to open position until the prongs are clear of the bars 33. Then, the ejecting spring 51 will eject the plug through the medium of the plunger 45, and as the plunger 46 moves outwardly, the holders 55 will be pulled 0d of the fingers 4%) so that the springs 38 can push the bars 33 into their normal position ready to be used again.

With the present invention, electrical appliances which use extension cords such as electric hand tools, sweepers, irons, lights and the like can be more advantageously used. Thus, the plug will stay firmly locked even though the cord may be moved. To disengage the plug it is only necessary to push the plug inward and then the plug will automatically jump out by itself.

1 claim:

1. In combination, a housing having inner and outer walls, there being a pair of spaced parallel apertures in the outer wall of said housing, there being a circular opening in the outer Wall of said housing positioned between said apertures, a plug including a base and a pair of spaced parallel prongs extending from said base for insertion through said apertures, a stud extending from said base and positioned between said pair of prongs, said stud being shorter than said prongs, there being a notch in the inner surface of each of said prongs, a pair of contacts extending from the inner wall of said housing and adapted to be connected to a source of electrical energy, L-shaped ribs mounted in said inner wall and connected to said contacts, a pair of spaced parallel ears extending from each of said ribs, a spring contact member extending from each pair of ears, an insulated bar pivotally connected to each pair of ears, each of said bars being provided with a cutout defining a shoulder for engagement with the notch in said prong, a body portion extending inwardly from each of said bars, there being a recess in the inner wall of said housing, coil springs seated in said recess and abutting said body portion, a finger of reduced size extending outwardly from each of said bars, there being a central recess in the inner wall of said housing, a pin having one end projecting into said last named recess, a plunger arranged on the outer end of said pin and including a cylindrical portion mounted for reciprocatory movement through the circular opening in the outer wall of said housing, a collar of increased diameter arranged at the inner end of said plunger, a coil spring circumposed on said pin and having one end abutting said collar, a pair of spaced parallel securing elements extending from said collar and secured thereto, a bracket including a sleeve surrounding said pin and engaging said securing elements, there being holders on said bracket for at times receiving said fingers.

2. In combination, a housing having inner and outer walls, there being a pair of apertures in the outer wall of said housing, there being an opening in the outer wall of said housing positioned between said apertures, a plug including a base and a pair of prongs extending from said base for insertion through said apertures, a stud extending from said base and positioned between said pair of prongs, said stud being shorter than said prongs, there being a notch in each of said prongs, a pair of contacts extending from said housing and adapted to be connected to a source of electrical energy, ribs mounted in said inner wall and connected to said contacts, a pair of ears extending from each of said ribs, a spring contact member extending from each pair of cars, an insulated bar pivotally connected to each pair of ears, each of said bars being provided with a cutout defining a shoulder for engagement with the notch in said prong, a body portion extending from each of said bars, there being a recess in the inner wall of said housing, coil springs seated in said recess and abutting said body portion, a finger or" reduced size extending outwardly from each of said bars, there being a recess in the inner wall of said housing, a pin having one end projecting into said last named recess, a plunger arranged on said pin and including a cylindrical portion mounted for reciprocatory movement through the circular opening in the outer wall of said housing, a collar of increased diameter arranged at the inner end of said plunger, a coil spring circumposed on said pin and having one end abutting said collar, a pair of securing elements extending from said collar and secured thereto, a bracket including a sleeve surrounding said pin and engaging said securing elements, there being holders on said bracket for at times receiving said fingers.

References Cited in the file of this patent UNITED STATES PATENTS I 

